This invention pertains to the prevention of electrical power losses from an electrical power transmission well. More particularly, a high voltage well which is used to either produce or inject salt water is isolated by insulating couplings and an insulated tortuous salt water path.
Large deposits of viscous hydrocarbonaceous substances, such as for example the Ugnu formation in Alaska, are known to exist in subterranean formations. Many techniques have been proposed for producing tar sands and viscous oils. Relatively recently, it has been proposed, for example, in U.S. Pat. Nos. 3,642,066; 3,874,450; 3,848,671; 3,948,319; 3,958,636; 4,010,799 and 4,084,637 to use electrical current to add heat to a subsurface pay zone containing tar sands or viscous oil to render the viscous hydrocarbon more flowable. The oil components flow to a producing well where the oil is produced. The produced fluids may contain high salt content formation waters of low electrical resistance. Sometimes low resistance salt water is also injected through injection wells to maintain formation pressure and drive oil into the producing wells. Both the production wells and the injection wells may be used as power transmission wells. Both types of wells may frequently be connected through flowlines to grounded metal equipment, for example, a salt water disposal or producing well. In Alaska, for example, a water injection well may be connected to a flowline which is connected to a sea water pump which is grounded in the sea or ocean. When electrical power is applied to a well producing or injecting salt water, electrical currents are lost through the flowlines to the grounded metal equipment. This power loss decreases the efficiency of the electrical heating process. Disrupting the metal flowline path with insulating flanges, for example, does not sufficiently alleviate the problem of such power loss. Power transmission wells for subsurface heating use voltages of up to several thousand volts and the low resistance salt water in the flowline form an alternate electrical path that is low enough in resistance to still cause undesirably high power or current losses.
It is the primary purpose of this invention to provide a system for isolating an electrical power transmission well from other grounded metal equipment and thereby decrease power losses to such equipment.